Surface Additive For Three-Dimensional Polymeric Printing Powders

ABSTRACT

A composition including a three-dimensional polymeric printing powder; an organic polymeric additive on at least a portion of an external surface of the three-dimensional polymeric printing powder; wherein the organic polymeric additive is optionally cross-linked; and optionally, an inorganic additive on at least a portion of an external surface of the three-dimensional polymeric printing powder. A process for preparing a three-dimensional polymeric printing powder having an organic polymeric additive disposed thereon. A process for employing the three-dimensional polymeric printing powder including selective laser sintering.

RELATED APPLICATIONS

Commonly assigned U.S. patent application Ser. No. _____ (AttorneyDocket number 20180840US01, entitled “Toner Compositions And ProcessesIncluding Polymeric Toner Additives”), filed concurrently herewith,which is hereby incorporated by reference herein in its entirety,describes a polymeric composition including a copolymer comprising afirst monomer having a high carbon to oxygen ratio of from about 3 toabout 8; a second monomer comprising two or more vinyl groups, whereinthe second monomer is present in the copolymer in an amount of fromgreater than about 8 percent by weight to about 60 percent by weight,based on the weight of the copolymer; and, optionally, a third monomercomprising an amine, wherein the third monomer, if present, is presentin an amount of from about 0.5 percent by weight to about 5 percent byweight, based on the weight of the copolymer. A toner including thecopolymer as a toner surface additive. An emulsion aggregation tonerprocess including the copolymer as a toner surface additive.

Commonly assigned U.S. patent application Ser. No. ______ (AttorneyDocket number 20180734US01, entitled “Toner Compositions And ProcessesHaving Reduced Or No Titania Surface Additives”), filed concurrentlyherewith, which is hereby incorporated by reference herein in itsentirety, describes a toner including toner particles comprising atleast one resin, in combination with an optional colorant, and anoptional wax; and a copolymer toner additive on at least a portion of anexternal surface of the toner particles, the copolymer toner additivecomprising a first monomer having a high carbon to oxygen ratio of fromabout 3 to about 8; and a second monomer comprising two or more vinylgroups, wherein the second monomer is present in the copolymer in anamount of from greater than about 8 percent by weight to about 60percent by weight, based on the weight of the copolymer; wherein thecopolymer toner additive has a volume average particle diameter of fromabout 20 nanometers to less than about 70 nanometers. An emulsionaggregation toner process including the copolymer as a toner surfaceadditive.

Commonly assigned U.S. patent application Ser. No. ______ (AttorneyDocket number 20180782US01, entitled “Cross-Linked Polymeric LatexPrepared With A Low Surface Tension Surfactant”), filed concurrentlyherewith, which is hereby incorporated by reference herein in itsentirety, describes a polymeric composition including a copolymercomprising a first monomer having a high carbon to oxygen ratio of fromabout 3 to about 8; a second monomer comprising two or more vinylgroups, wherein the second monomer is present in the copolymer in anamount of from greater than about 8 percent by weight to about 40percent by weight, based on the weight of the copolymer; and optionally,a third monomer comprising an amine, wherein the third monomer ispresent in an amount of from about 0.1 percent by weight to about 1.5percent by weight, based on the weight of the copolymer; and asurfactant, wherein the surfactant has a minimum surface tension atcritical micelle concentration of less than about 30 mN/m. A tonerincluding the copolymer as a toner surface additive. An emulsionaggregation toner process including the copolymer as a toner surfaceadditive.

Commonly assigned U.S. patent application Ser. No. ______ (AttorneyDocket number 20180885US01, entitled “Process For Preparing AThree-Dimensional Printing Composition”), filed concurrently herewith,which is hereby incorporated by reference herein in its entirety,describes a process including providing a three-dimensional printingpowder dispersion comprising a three-dimensional printing powder, anoptional dispersing agent, and water; providing an emulsion of anorganic polymeric additive; combining the three-dimensional printingpowder dispersion and the emulsion of organic polymeric additive to forma mixture comprising the three-dimensional printing powder dispersionand the emulsion of organic polymeric additive; and drying the mixtureof the three-dimensional printing powder dispersion and the emulsion oforganic polymeric additive.

Commonly assigned U.S. patent application Ser. No. ______ (AttorneyDocket number 20180881US01, entitled “Surface Additive ForThree-Dimensional Metal Printing Compositions”), filed concurrentlyherewith, which is hereby incorporated by reference herein in itsentirety, describes a composition including a three-dimensional metalprinting powder; an organic polymeric additive on at least a portion ofan external surface of the three- dimensional metal printing powder; andoptionally, an inorganic additive on at least a portion of an externalsurface of the three-dimensional metal printing powder. A process forpreparing a three-dimensional metal printing powder having an organicpolymeric additive disposed thereon. A process for employing thethree-dimensional metal printing powder including selective lasersintering.

BACKGROUND

Disclosed herein is a composition comprising a three-dimensionalpolymeric printing powder; an organic polymeric additive on at least aportion of an external surface of the three-dimensional polymericprinting powder; wherein the organic polymeric additive is optionallycross-linked; and optionally, an inorganic additive on at least aportion of an external surface of the three-dimensional polymericprinting powder.

Further disclosed is a process for preparing a three-dimensionalprinting composition comprising providing a three-dimensional polymericprinting powder; providing an organic polymeric additive on at least aportion of an external surface of the three-dimensional polymericprinting powder; and optionally, further providing an inorganic additiveon at least a portion of an external surface of the three-dimensionalpolymeric printing powder; wherein the organic polymeric additive isprepared by emulsion polymerization.

Further disclosed is a method comprising providing a three-dimensionalpolymeric printing powder having an organic polymeric additive on atleast a portion of an external surface of the three-dimensionalpolymeric printing powder; and optionally, further having an inorganicadditive on at least a portion of an external surface of thethree-dimensional polymeric printing powder; and exposing thethree-dimensional polymeric printing powder having the organic polymericadditive and optional inorganic additive to a laser to fuse thethree-dimensional polymeric printing powder.

Selective Laser Sintering (SLS) is one of the most popular additivemanufacturing processes that creates a three-dimensional (3D) objectlayer-by-layer. The process applies layers of powder material on top ofeach other sequentially, where each layer of powder is sintered orcoalesced together with a laser according to the computer aided drawing(CAD) geometry of the part.

SLS is a powder bed based additive manufacturing technique to producecomplex three-dimensional parts. In SLS, a rasterized laser is used toscan over a bed of polymer powder, sintering it to form solid shapes ina layer-wise fashion. When the laser beam scans the powder, the powdermelts due to the rising temperature, and layer by layer, the final partapproaches full density and should result in properties of the bulkmaterial (that is, the polymer). In theory, every thermoplastic polymerthat can be transformed into a powder form can be processed via thistechnique, but the reality is that every material behaves differently,often unpredictably, during melting, coalescence, and consolidation, andoften requires unique SLS processing parameters. The bed temperature andlaser energy input, for example, can be selected based on the processingwindow of the polymer's thermal profile as well as its energyabsorption. Laser parameters can also be selected based on the powder'sparticle size and shape.

U.S. Patent Publication 2018/0022043, which is hereby incorporated byreference herein in its entirety, describes in the Abstract thereof amethod of selective laser sintering. The method comprises providingcomposite particles made by emulsion aggregation, the compositeparticles comprising at least one thermoplastic polymer and at least onecarbon particle material. The composite particles are exposed to a laserto fuse the composite particles.

There are different types of polymer particles that are generally usedin the SLS process. Semi-crystalline resins such as polyamides includingPA12, PA11, and PA6, polylactic acid (PLA), polyether ether ketone(PEEK), polyethylene (PE), polypropylene (PP), and others are used. Themost common polymer powder employed is polyamide PA12. The common namefor polyamide is nylon. For example polyamide PA12 is also known asnylon 12, polyamide PA6 is also known as nylon 6. A layer-upon-layerstructure is formed by sintering the polymer particles together with alaser above the melting point of the polymer according to the CADgeometry file of the part.

In 3D applications using particulate powders there are a number ofproblems that can occur due to inter-particle interactions within thepowder. These potential problems include adverse effects on particulateflow, which enables the powder to flow within the 3D printer and in thepowder bed or in the delivery nozzle, as well as how tightly the powderspack together for the sintering step. High inter-particle forces lead topoor flow, which can limit the speed at which powder is supplied, or cancause the particles to clog up the delivery system. High inter-particleforces can mean that the particles do not pack well, which can lead tolarge pores and poor sintering, leaving a weak, irregularly shaped,rough surface and porous final part. Finally, the powder from a bed canbe reused. For polymeric powders, the recycling can result in theparticles sticking together due to proximate heating as the part isformed. After one or more recycling steps the particle flow can bedegraded, and particles may also start to stick together in clumps,leading to a greater tendency to slow or clog the delivery system, or toform non-uniform, porous and weak parts.

Nanoparticulate silica powders have been used as additives in 3Dprinting applications for improving flow. See Blümel et al. Rapid Proto.J. 21 (2015) 697-704: “Increasing flowability and bulk density of PE-HDpowders by a dry particle coating process. And further, that this canhave a large impact on Laser Beam Melting (LBM) processes” of thepowder, and thus the quality of the final part, in particular improvingthe porosity and density of the part, and thus the part's overallstrength ( ).” However, as pointed out in the article, the silicachemistry is not necessarily a good match with the chemistry of the 3Dpowder, and thus is not necessarily effective. Further silica isrefractory, so it melts at a very high temperature, thus it will notflow in the sintering steps for a 3D polymeric powder, which mayinterfere with proper sintering.

While currently available SLS materials, including three-dimensionalpolymeric printing powders, may be suitable for their intended purposes,there remains a need for improved three-dimensional polymeric printingpowders. Further, a need remains for additives that can provide improvedflow and blocking of three-dimensional polymeric printing powders.Further, a need remains for additives that enable recycling of thethree-dimensional powder. Further, a need remains for additives thatenable three-dimensional printing of high density and strong parts.

The appropriate components and process aspects of the each of theforegoing U. S. Patents and Patent Publications may be selected for thepresent disclosure in embodiments thereof. Further, throughout thisapplication, various publications, patents, and published patentapplications are referred to by an identifying citation. The disclosuresof the publications, patents, and published patent applicationsreferenced in this application are hereby incorporated by reference intothe present disclosure to more fully describe the state of the art towhich this invention pertains.

SUMMARY

Described is a composition comprising a three-dimensional polymericprinting powder; an organic polymeric additive on at least a portion ofan external surface of the three-dimensional polymeric printing powder;wherein the organic polymeric additive is optionally cross-linked; andoptionally, an inorganic additive on at least a portion of an externalsurface of the three-dimensional polymeric printing powder.

Also described is a process comprising providing a three-dimensionalpolymeric printing powder; providing an organic polymeric additive on atleast a portion of an external surface of the three-dimensionalpolymeric printing powder; and optionally, further providing aninorganic additive on at least a portion of an external surface of thethree-dimensional polymeric printing powder; wherein the organicpolymeric additive is prepared by emulsion polymerization.

Also described is a method comprising providing a three-dimensionalpolymeric printing powder having an organic polymeric additive on atleast a portion of an external surface of the three-dimensionalpolymeric printing powder; and optionally, further having an inorganicadditive on at least a portion of an external surface of thethree-dimensional polymeric printing powder; and exposing thethree-dimensional polymeric printing powder having the organic polymericadditive and optional inorganic additive to a laser to fuse thethree-dimensional polymeric printing powder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a scanning electron micrograph of PA12 polyamide particlesat 50× magnification.

FIG. 2 shows a scanning electron micrograph of PA12 polyamide particlesat 100× magnification.

FIG. 3 shows a scanning electron micrograph of PA12 polyamide particlesat 400× magnification.

FIG. 4 shows a scanning electron micrograph of PA12 polyamide particlesat 600× magnification.

FIG. 5 shows a scanning electron micrograph of PA12 polyamide with theOrganic Polymeric Additive added in dry blending in accordance with thepresent disclosure at 15,000X.

DETAILED DESCRIPTION

A polymeric surface additive prepared by emulsion polymerization to beused with, or instead of a silica or other inorganic additive, on thesurface of a three-dimensional (3D) polymeric powder, is provided. Thepolymeric surface additive improves the flow or blocking performance ofthe 3D powder, and also may render the surface more hydrophobic, andthus improves the density and strength of the produced parts. There area number of potential advantages for an organic additive compared to aninorganic additive such as silica. First, the organic chemistry of themonomers can be selected to be compatible with that of the 3D powder foreffective blending. This can be done by changing the matrix polymer ofthe polymeric latex or by changing the amount of a co-monomer that haseither acid or basic functionality. Thus, the hydrophobicity and theacid-base chemistry can be tuned as required. The organic latex additivecan be crosslinked or non-crosslinked. The crosslinked additive is morerobust to aggressive handling, as, to be effective, the additive muststay as a spherical particle on the 3D particle surface. If the particleflattens, then it will no longer be functional as a surface additive.However, under most conditions in 3D printing, such robustness may notbe required, in which case a partially cross-linked or non-crosslinkedorganic polymeric latex as described herein is selected as the surfaceadditive. The advantage of the non-crosslinked organic polymeric latexis that it can be formulated to melt in the sintering process, and thusbe less likely to interfere with the proper sintering of parts than thecross-linked material, or than an inorganic surface additive, such assilica, titania or alumina.

In embodiments, the organic polymeric additives herein comprise amonomer selected from the group consisting of an acrylate monomer, amethacrylate monomer, and combinations thereof. The organic polymericsurface additives herein can employ as the matrix monomer of thepolymeric composition cyclohexyl methacrylate (CHMA), which is ahydrophobic monomer which can mimic the hydrophobicity of silane treatedsilica. To this can be added a monomer composition of divinyl benzene(DVB), which creates a highly cross-linked structure, to create a hardparticle that will remain as a spherical particle with aggressivehandling. The cross-linker can be left out of the formulation ifcross-linking is not required or desired. An optional third monomer ofthe polymeric composition can be dimethyaminoethyl methacrylate(DMAEMA). The third monomer, such as DMAEMA, is optional forapplications directed to 3D particles, but potentially would be a goodmatch to a polyamide particle, for example, due to the nitrogen group,which would interact strongly with the amide groups, resulting in goodattachment of the polymeric additive to the polyamide particle surface.Alternately, CHMA organic additive latex can be prepared with acidfunctionality, using (3-CEA or acrylic acid. The acid group wouldinteract strongly with the amide groups in polyamide, due to anacid-base interaction, again effectively attaching the polymer additiveto the polyamide particle surface. Alternately, for high densitypolyethylene, in embodiments it would be desirable not to have afunctional group, and have just the hydrophobic CHMA monomer, whichwould be relatively compatible. Compared to a comparable size silica, anorganic additive requires less additive to effectively cover the surfacecompared to a silica, as the organic polymer latex density is typicallyless than 1.4 g/cm³, while silica is 2.2 g/cm³, and other inorganicadditives are even higher density, and so require proportionally higherweight percent loading.

For blocking performance, it is also desirable to recycle the 3D powder.Powder that has been in close proximity to the heating source in thesintering process may clump together due to some melting. On recycling,these clumps may not readily break up, such that they are sufficientlyblocked that they are effectively stuck together. When this material isrecycled, this can lead to poor 3D powder flow. In embodiments herein,the organic polymeric latex additive is used as a surface additive toimprove blocking. For blocking it may be preferable to have the organicpolymer additive heavily cross-linked, so that it doesn't melt at thehigh temperatures that may be encountered in SLS printing.

As used herein, a polymer or co-polymer is defined by the monomer(s)from which a polymer is made. Thus, for example, while in a polymer madeusing an acrylate monomer as a monomer reagent, an acrylate moiety perse no longer exists because of the polymerization reaction, as usedherein, that polymer is said to comprise the acrylate monomer. Thus, anorganic polymeric additive made by a process disclosed herein can beprepared, for example, by the polymerization of monomers includingcyclohexyl methacrylate, divinyl benzene, and dimethylaminoethylmethacrylate. The resulting organic polymeric additive can be said tocomprise cyclohexyl methacrylate as that monomer was used to make theorganic polymeric additive; can be said to be composed of or ascomprising divinyl benzene as divinyl benzene is a monomer reagent ofthat polymer; and so on. Hence, a polymer is defined herein based on oneor more of the component monomer reagents, which provides a means toname the organic polymeric additives herein.

In embodiments, an organic polymeric additive is provided comprising apolymer or copolymer comprising a first monomer having a high carbon tooxygen ratio of from about 3 to about 8; an optional second monomercomprising two or more vinyl groups, wherein the second monomer, ifpresent, can be present in the copolymer in an amount of from greaterthan about 8 percent by weight to about 40 percent by weight, based onthe weight of the copolymer; and optionally, a third monomer comprisingan amine, wherein the third monomer, if present, is present in an amountof from about 0.5 percent by weight to about 1.5 percent by weight,based on the weight of the copolymer. In embodiments, the organicpolymer additive further comprises a surfactant. In certain embodiments,the surfactant has a minimum surface tension of less than about 45 mN/m.In other embodiments the surfactant has a minimum surface tension ofless than 30 mN/m. In embodiments the minimum surface tension ismeasured at the critical micelle concentration.

The organic polymeric surface additive, also termed herein an organicpolymeric additive or a polymer or copolymer organic additive, inembodiments, is a latex formed using emulsion polymerization. The latexincludes at least one monomer with a high carbon to oxygen (C/O) ratiooptionally combined with a monomer possessing two or more vinyl groups,optionally combined with a monomer containing an amine functionality.The aqueous latex is then dried and can be used in place of, or inconjunction with, other additives. The use of a high C/O ratio monomerprovides good relative humidity (RH) stability, and the use of the aminefunctional monomer may provide desirable adhesion of the organic polymeradditive to the surface of the 3D particles. The use of a monomerpossessing two or more vinyl groups, sometimes referred to herein, inembodiments, as a crosslinking monomer or a crosslinking vinyl monomer,provides a crosslinked property to the polymer, thereby providingmechanical robustness required in the developer housing.

In embodiments, the organic additive comprises at least one non-cross-linkable polymerizable monomer; or the organic additive comprises atleast one cross-linkable polymerizable monomer; or the organic additivecomprises a combination of at least one non-cross-linkable polymerizablemonomer and at least one cross-linkable polymerizable monomer.

In certain embodiments, the organic polymeric additive is free ofcross-linkable polymerizable monomers.

The resulting organic polymer or copolymer additive may be used as anadditive with three-dimensional printing compositions, providing theresulting three-dimensional printing compositions with desiredcharacteristics including improved flow and blocking and improvedhydrophobicity, as well as the ability to prepare high density andstrong parts. The polymeric additives herein may be used at a lowerdensity compared with other additives, so that much less material byweight is required for equivalent surface area coverage, compared toinorganic additives, including oxides such as titania and silica. Thepolymeric additives of the present disclosure may also provide thethree-dimensional polymeric printing powders with a wide range ofproperties including robustness, desired melting properties, among otherproperties, depending on the monomers used in the formation of theorganic polymers or copolymers.

As noted above, the organic polymeric or copolymeric additive may be ina latex. In embodiments, a latex polymer or copolymer utilized as theorganic polymeric surface additive may include a first monomer having ahigh C/O ratio, such as an acrylate or a methacrylate. The C/O ratio ofsuch a monomer may be from about 3 to about 8, in embodiments, fromabout 4 to about 7, or from about 5 to about 6. In embodiments, themonomer having a high C/O ratio may be an aliphatic cycloacrylate.Suitable aliphatic cycloacrylates which may be utilized in forming thepolymer additive include, for example, cyclohexyl methacrylate,cyclopropyl acrylate, cyclobutyl acrylate, cyclopentyl acrylate,cyclohexyl acrylate, cyclopropyl methacrylate, cyclobutyl methacrylate,cyclopentyl methacrylate, isobornyl methacrylate, isobornyl acrylate,benzyl methacrylate, phenyl methacrylate, combinations thereof, and thelike.

The first monomer having a high carbon to oxygen ratio, in embodiments,a cycloalkyl acrylate, may be present in the polymer or copolymerutilized as an organic polymeric additive in any suitable or desiredamount. In embodiments, the cycloalkyl acrylate may be present in thepolymer or copolymer in an amount of from about 40 percent by weight ofthe copolymer to about 100 percent by weight of the copolymer, or fromabout 50 percent by weight of the copolymer to about 95 percent byweight of the copolymer, or from about 60 percent by weight of thecopolymer to about 95 percent by weight of the copolymer. Inembodiments, the first monomer is present in the copolymer in an amountof from about 40 percent by weight to about 90 percent by weight, basedon the weight of the copolymer, or from about 45 percent by weight toabout 90 percent by weight, based on the weight of the copolymer.

The organic polymer or copolymer additive optionally includes a secondmonomer, wherein the second monomer comprises a crosslinking monomer. Inembodiments, the second monomer comprises a crosslinking monomerpossessing vinyl groups, in certain embodiments, two or more vinylgroups.

Suitable monomers having vinyl groups for use as the crosslinking vinylcontaining monomer include, for example, diethyleneglycol diacrylate,triethyleneglycol diacrylate, tetraethyleneglycol diacrylate,polyethyleneglycol diacrylate, 1,6-hexanediol diacrylate,neopentylglycol diacrylate, tripropyleneglycol diacrylate,polypropyleneglycol diacrylate,2,2′-bis(4-(acryloxy/diethoxy)phenyl)propane, trimethylolpropanetriacrylate, tetramethylolmethane tetraacrylate, ethyleneglycoldimethacrylate, diethyleneglycol dimethacrylate, triethyleneglycoldimethacrylate, tetraethyleneglycol dimethacrylate, polyethyleneglycoldimethacrylate, 1,3-butyleneglycol dimethacrylate, 1,6-hexanedioldimethacrylate, neopentylglycol dimethacrylate, polypropyleneglycoldimethacrylate, 2,2′,-bis(4-(methacryloxy/diethoxy)phenyl)propane,2,2′-bis(4-(methacryloxy/polyethoxy)phenyl)propane, trimethylolpropanetrimethacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinyl naphthalene, divinyl ether, combinations thereof, andthe like. In a specific embodiment, the cross-linking monomer is divinylbenzene.

The organic polymer or copolymer additive herein optionally comprises asecond monomer which results in the organic additive being a highlycrosslinked copolymer. In embodiments, the second monomer comprising twoor more vinyl groups is present in the copolymer in an amount of greaterthan about 8 percent by weight to about 60 percent by weight, based uponthe weight of the copolymer, or greater than about 10 percent by weightto about 60 percent by weight, based upon the weight of the copolymer,or greater than about 20 percent by weight to about 60 percent byweight, based upon the weight of the copolymer, or greater than about 30percent by weight to about 60 percent by weight, based upon the weightof the copolymer. In certain embodiments, the second monomer is presentin the copolymer in an amount of greater than about 40 percent by weightto about 60 percent by weight, or greater than about 45 percent byweight to about 60 percent by weight, based on the weight of thecopolymer.

In embodiments, the organic polymeric additive comprises across-linkable monomer containing 2 or more vinyl groups; and thecross-linkable monomer containing 2 or more vinyl groups is present inthe organic polymeric additive in an amount of greater than zero up toabout 40 percent, by weight, based on the total weight of the organicpolymeric additive.

In an alternate embodiment, as mentioned above, the organic polymer orcopolymer additive does not contain a crosslinking monomer.

The organic polymer or copolymer additive herein optionally furthercomprises a third monomer comprising an amine functionality. Monomerspossessing an amine functionality may be derived from acrylates,methacrylates, combinations thereof, and the like. In embodiments,suitable amine-functional monomers include dimethylaminoethylmethacrylate (DMAEMA), diethylaminoethyl methacrylate,dipropylaminoethyl methacrylate, diisopropylaminoethyl methacrylate,dibutylaminoethyl methacrylate, combinations thereof, and the like.

In embodiments, the organic copolymer additive herein does not containthe third monomer. In other embodiments, the organic copolymer additiveherein contains the third monomer comprising an amine-functionalmonomer. The amine-functional monomer, if present, may be present in theorganic copolymer in an amount of from about 0.1 percent by weight ofthe copolymer to about 40 percent by weight of the copolymer, or fromabout 0.5 percent by weight of the copolymer to about 5 percent byweight of the copolymer, or from about 0.5 percent by weight of thecopolymer to about 1.5 percent by weight of the copolymer.

In embodiments, the organic copolymer additive comprises an acidicmonomer, a basic monomer, or a combination thereof. In certainembodiments, the organic polymeric additive comprises a basic monomerhaving a nitrogen-containing group; and the basic monomer having anitrogen-containing group is present in the organic polymeric additivein an amount of less than about 1.5 percent, by weight, based on thetotal weight of the organic polymeric additive. In other embodiments,the organic polymeric additive comprises an acidic monomer having anacidic group selected from the group consisting of acrylic acid,beta-carboxyethyl acrylate, and combinations thereof; and the acidicmonomer is present in the organic polymeric additive in an amount ofless than about 4 percent, by weight, based on the total weight of theorganic polymeric additive.

In embodiments, the organic copolymer additive comprises cyclohexylmethacrylate as a hydrophobic monomer and divinyl benzene as across-linkable monomer. In certain embodiments, the copolymer additivecomprises cyclohexyl methacrylate as a hydrophobic monomer, divinylbenzene as a cross-linkable monomer, and dimethylaminoethyl methacrylateas a nitrogen-containing monomer. In other embodiments, the copolymeradditive is free of the cross-linkable monomer.

Methods for forming the organic polymer or copolymer surface additiveare within the purview of those skilled in the art and include, inembodiments, emulsion polymerization of the monomers utilized to formthe polymeric additive.

In the polymerization process, the reactants may be added to a suitablereactor, such as a mixing vessel. The appropriate amount of startingmaterials may be optionally dissolved in a solvent, an optionalinitiator may be added to the solution, and contacted with at least onesurfactant to form an emulsion. A copolymer may be formed in theemulsion (latex), which may then be recovered and used as the polymericadditive for a three-dimensional printing composition.

Where utilized, suitable solvents include, but are not limited to, waterand/or organic solvents including toluene, benzene, xylene,tetrahydrofuran, acetone, acetonitrile, carbon tetrachloride,chlorobenzene, cyclohexane, diethyl ether, dimethyl ether, dimethylformamide, heptane, hexane, methylene chloride, pentane, combinationsthereof, and the like.

In embodiments, the latex for forming the organic polymeric additive maybe prepared in an aqueous phase containing a surfactant orco-surfactant, optionally under an inert gas such as nitrogen. Thus, inembodiments, the organic polymeric additive comprises latex particlesproduced by emulsion polymerization of at least one monomer and asurfactant.

The surfactant selected for the organic polymer or copolymer may be anysuitable or desired surfactant. The surfactant can be a member of thegroup consisting of an anionic surfactant, a cationic surfactant, anon-ionic surfactant, and combinations thereof.

In embodiments, the surfactant comprises a member of the groupconsisting of sodium dodecylbenzene sulfonate, sodium dodecyl sulphate,and combinations thereof.

In certain embodiments, the surfactant selected for the present polymeror co-polymer surface additive is a surfactant having a selected surfacetension which enables preparation of a smaller sized particle, inembodiments, wherein the polymeric composition comprises latex particlesof the copolymer and the surfactant wherein the latex particles having avolume average particle diameter of less than 70 nanometers.

The organic polymeric additive can comprise latex particles having avolume average particle diameter of from about 30 nanometers to about140 nanometers. In embodiments, the organic polymer or copolymeradditive herein has a particle size of less than 70 nanometers, or lessthan 50 nanometers, or from about 20 to less than 70 nanometers, or fromabout 20 to about 50 nanometers, or from about 20 to less than 50nanometers D50 by volume measured using a Nanotrac NPA252 fromMicrotrac, Inc.

In embodiments, an organic polymeric composition herein comprises latexparticles of the copolymer and the surfactant, wherein the latexparticles have a volume average particle diameter of from about 20nanometers to less than 70 nanometers, or from about 20 nanometers toabout 50 nanometers, or from about 20 nanometers to less than 50nanometers.

In embodiments, a surfactant is selected having a minimum surfacetension at critical micelle concentration of less than about 30millinewtons per meter (mN/m). In embodiments, the surfactant selectedhas a minimum surface tension at critical micelle concentration of fromabout 10 to less than 30 mN/m, or from about 15 to less than 30 mN/m, orfrom about 15 to about 25 mN/m, or from about 15 to about 21 mN/m. Inembodiments, the surfactant has a minimum surface tension at criticalmicelle concentration of less than 30 mN/m, or about 20 to about 25mN/m. In embodiments, the surfactant selected has a minimum surfacetension of less than about 45 mN/m.

In embodiments, the organic polymeric additive herein comprises latexparticles produced by emulsion polymerization of at least one monomerand a surfactant; wherein the surfactant comprises a member of the groupconsisting of an anionic surfactant, a cationic surfactant, a non-ionicsurfactant, and combinations thereof; and wherein the surfactant has aminimum surface tension of less than about 45 mN/m.

In embodiments, the organic polymeric additive comprises latex particlesproduced by emulsion polymerization of at least one monomer and asurfactant; wherein the surfactant comprises a member of the groupconsisting of sodium dodecylbenzene sulfonate, sodium dodecyl sulphate,and combinations thereof.

Surface tension of the surfactant can be measured by any suitable ordesired method as known in the art. For example, surfactant surfacetension can be measured by force tensiometry based on measuring theforces exerted on a probe that is positioned at the liquid-gasinterface, as discussed in more detail in the Attension® White Paper andreferences included therein, entitled “Surface and interfacialtension,—what is it and how to measure it,” by Susanna Laurén, BiolinScientific. Two probe configurations are commonly used, the du Noüy ringand the Wilhelmy plate. A metal (such as platinum) rod can also be usedinstead of a Wilhelmy plate when sample volume is limited. Surfacetension can also be measured optically, this is called opticaltensiometry and is based on the analysis of a pendant drop shape.

As known in the art, critical micelle concentration (CMC) is defined asthe concentration of surfactants above which micelles form and alladditional surfactants added to the system go to micelles.

As known in the art, a micelle is an aggregate (or supramolecularassembly) of surfactant molecules dispersed in a liquid colloid. Atypical micelle in aqueous solution forms an aggregate with thehydrophilic “head” regions in contact with surrounding solvent,sequestering the hydrophobic single-tail regions in the micelle center.

As discussed above, the surfactant selected can be any suitable ordesired surfactant. In embodiments, the surfactant is selected toachieve a desired characteristic of smaller sized co-polymer surfaceadditive. In embodiments, the surfactant is selected from the groupconsisting of dodecylbenzene sulfonate: trisiloxanes such as((CH₃)₃SiO₂)₂Si—(CH₃)(CH₂)₃(OCH₂CH₂)_(n)OH with n=4-12, that have asurface tension at the critical micelle concentration of 20-21 mN/m,oxyethylated alcohols, C₁₄EO₈, C₁₂EO₅ and C₁₀EO₄,dimethyldidodecyl-ammonium bromide (DDAB); perfluorocarboxylic acids andsalts thereof, C₆F₁₃COOLi, C₇F₁₅COOH, C₇F₁₅COONa, C₈F₁₇COOH, C₈F₁₇COOLi,C₈F₁₇COONa, C₈F₁₇COONH₄, C₈F17COONH₃C₂H₄OH, C₁₀F₂₁COOLi, C₁₀F₂₁COONH₄,C₁₀F₂₁COONH₃C₂H₄OH, C₁₂F₂₅COOLi, salts of perfluoroalcanesulfonic acid,C₈F₁₇SO₃Li, C₈F₁₇SO₃Na, C₈F₁₇SO₃NH₄, C₈F₁₇SO₃NH₃C₂H₄OH, other specificfluorosurfactants include Novec™ FC-4430, FC-4432, FC-4434 non-ionic,polymeric surfactants from 3M™, FC-5120 anionic ammoniumfluoroalkylsulfonate, specificallynonafluorobutyl)sulfonyflamino-2-hydroxy-1-propanesulfonic acid, ammoniasalt, from 3M™, Zonyl® FSN-100, Zonyl® FS-300, non-ionic ethoxylatesfrom DuPont™, Zonyl® FS-500 an amphoteric betaine from DuPont™, CapstoneFS-10 perfluoroalkylsulfonic acid from DuPont™, Capstone FS-30 non-ionicethoxylate from DuPont™, Capstone® FS-60 anionic blend from DuPont™,Capstone® FS-61 anionic phosphate from DuPont™, Capstone® FS-63 anionicphosphate from DuPont™, Capstone® FS-64 anionic phosphate DuPont™,Capstone® FS-65 non-ionic from DuPont™. Highly branched hydrocarbonsurfactants, including isostearyl sulphate Na salt, isostearyl sulphatetetrapropylammonium salt, and (CH₃)₃CCH₂CH(CH₃)CH₂PO₄Na may also beselected. In embodiments, with an appropriate choice of counterion, thesurface tension can be reduced to less than 30 mN/m at the criticalmicelle concentration, such as for dioctyl ammonium sulfosuccinate,dioctyl triethylamine sulfosuccinate, dioctyl trimethylaminesulfosuccinate, and dioctyl tetrapropylammonium sulfosuccinate. See, S.Alexander et al., Langmuir 2014, 30:3413-3421. To address environmentalconcerns of fluorosurfactants regarding potential issues aroundbioaccumulation and environmental impact, 3M has created anonafluorobutanesulphonyl fluoride intermediate that is converted intofluorosurfactants through a sulphonamide process. These new materialshave a perfluoroalkyl group with n≤4 and are not of as much concern froma regulatory perspective as are fluorochemicals with n>4. Previouslycommercialized under the FluoradTM trademark they are now replaced byNovec™, with surface tensions of 15-21 mN/m at concentration of 10-5 to10-3 mol/L in pH 8 buffered aqueous solutions. See, Farn, R. J. (Ed.),(2006), Chemistry and Technology of Surfactants, Blackwell PublishingLtd. In embodiment, the surfactant is a dodecylbenzene sulfonate. Inanother embodiment, the surfactant is sodium dodecylbenzene sulfonate.

In embodiments, the surfactants which may be utilized to form the latexdispersion can be used in an amount of from about 0.1 to about 15 weightpercent of all of the ingredients of the latex, the monomers, water,initiator and surfactant, and in embodiments of from about 0.2 to about5 weight percent of the all of the ingredients of the latex, themonomers, water, initiator and surfactant, and in embodiments from about0.3 to about 2 weight percent of all of the ingredients of the latex,the monomers, water, initiator and surfactant.

In certain embodiments, a polymeric composition herein comprises a latexincluding latex particles of the copolymer and the surfactant and water,wherein the surfactant is present in an amount of from about 0.1 toabout 15, or from about 0.2 to about 5, or from about 0.3 to about 2percent by weight, based upon the weight of all the latex ingredients,including the resin, the water, the surfactant, and the initiator. Inembodiments, the surfactant is present in an amount of from about 0.3 toabout 2 percent by weight, based upon the weight of all the ingredientsin the latex, including the monomers, the water, the initiator and thesurfactant.

In embodiments initiators may be added for formation of the latexutilized in formation of the organic polymeric additive. Examples ofsuitable initiators include water soluble initiators, such as ammoniumpersulfate, sodium persulfate and potassium persulfate, and organicsoluble initiators including organic peroxides and azo compoundsincluding Vazo peroxides, such as VAZO 64™, 2-methyl 2-2,-azobispropanenitrile, VAZO 88™, 2-2′-azobis isobutyramide dehydrate, andcombinations thereof. Other water-soluble initiators which may beutilized include azoamidine compounds, for example2,2′,-azobis(2-methyl-N-phenylpropionamidine) dihydrochloride,2,2′-azobis[N-(4-chlorophenyl)-2-methylpropionamidine]di-hydrochloride,2,2′,-azobis[N-(4-hydroxyphenyl)-2-methyl-propionamidine]dihydrochloride,2,2′,-azobis[N-(4-amino-phenyl)-2-methylpropionamidine]tetrahydrochloride,2,2′,-azobis[2-methyl-N(phenylmethyl)propionamidine]dihydrochloride,2,2′,-azobis[2-methyl-N-2-propenylpropionamidine]dihydrochloride,2,2′,-azobis[N-(2-hydroxy-ethyl)2-methylpropionamidine]dihydrochloride,2,2′-azobis[2(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride,2,2′,-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride,2,2′-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane]dihydrochloride,2,2,-azobis[2-(3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride,2,2′,-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl)propane]dihydrochloride,2,2′,-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride,combinations thereof, and the like.

Initiators can be added in suitable amounts, such as from about 0.1 toabout 8 weight percent, or from about 0.2 to about 5 weight percent, ofthe monomers.

In forming the emulsions, the starting materials, surfactant, optionalsolvent, and optional initiator may be combined utilizing any meanswithin the purview of those skilled in the art. In embodiments, thereaction mixture may be mixed for from about 1 minute to about 72 hours,in embodiments from about 4 hours to about 24 hours, while keeping thetemperature at from about 10° C. to about 100° C., or from about 20° C.to about 90° C., or from about 45° C. to about 75° C.

Those skilled in the art will recognize that optimization of reactionconditions, temperature, and initiator loading can be varied to generatepolymers of various molecular weights, and that structurally relatedstarting materials may be polymerized using comparable techniques.

The resulting latex, possessing the polymeric additive of the presentdisclosure, may have a C/O ratio of from about 3 to about 8, inembodiments from about 4 to about 7.

The resulting latex, possessing the polymeric additive of the presentdisclosure, may be dried and applied to three-dimensional polymericprinting powder utilizing any means within the purview of one skilled inthe art. In embodiments, the organic polymeric additive may be dryblended with the desired three-dimensional polymeric printing powder inany suitable or desired fashion such as mixing or blending in a mill.

In other embodiments, once the polymer or copolymer utilized as theadditive for the 3D powder has been formed, it may be recovered from thelatex by any technique within the purview of those skilled in the art,including filtration, drying, centrifugation, spray draying,combinations thereof, and the like.

In embodiments, once obtained, the copolymer utilized as the additivefor a 3D powder may be dried to powder form by any method within thepurview of those skilled in the art, including, for example, freezedrying, optionally in a vacuum, spray drying, combinations thereof, andthe like. The dried polymeric additive of the present disclosure maythen be applied to 3D powder utilizing any means within the purview ofthose skilled in the art including, but not limited to, mechanicalimpaction and/or electrostatic attraction.

Suitable mixing devices for dry blending the organic additive to thesurface of the 3D powder include apparatuses suitable for mixing andinclude a double cone mixer, a V-mixer, a drum mixer, a Turbulizer®, aCyclomix® (Hosokawa Micron Corporation); a Henschel mixer (Nippon Coke &Engineering Co., Ltd.), a Loedige Mixer (Matsubo Corporation), aRibocone mixer (Okawara Mfg. Co., Ltd.), a Nauta® mixer, a MechanoHybrid (Nippon Coke & Engineering Co., Ltd.), a Spiral Pin mixer(Pacific Machinery & Engineering Co., Ltd.), and a Super Mixer(manufactured by Kawata Mfg Co., Ltd.).

The organic polymer or copolymer additive herein is a smaller size thanprevious organic toner additives, such as described in U.S. Pat. No.8,663,886, which is hereby incorporated by reference herein in itsentirety. In embodiments, the organic polymer or copolymer additive hasan average or median volume average particle size (d50) of less than 70nanometers. In embodiments, the organic polymer or copolymer additivehas an average or median particle size (d50) of from about 20 nanometersto less than 70 nanometers, or from about 20 nanometers to about 65nanometers, or from about 20 to about 60 nanometers, or from about 20 toabout 50 nanometers. In specific embodiments, the copolymer additiveherein has an average or median particle size (d50) of less than 50nanometers, such as from about 20 to less than 50 nanometers.

In embodiments, a process herein for preparing a three-dimensionalprinting composition comprises providing a three-dimensional polymericprinting powder; providing an organic polymeric additive on at least aportion of an external surface of the three-dimensional polymericprinting powder; and optionally, further providing an inorganic additiveon at least a portion of an external surface of the three-dimensionalpolymeric printing powder; wherein the organic polymeric additive isprepared by emulsion polymerization.

Any suitable or desired 3D powder may be selected. In embodiments, thethree-dimensional polymeric printing powder is selected from the groupconsisting of polyamides (PA), polyethylenes (PE), polypropylenes (PP),polyalkanoates, polyesters, polyaryl ether ketones (PAEK),polycarbonates, polyacrylates, polymethacrylates, polystyrenes,polystyrene-acrylates, polyurethanes (PU), thermoplastic polyurethanes(TPU), polyether block amides (PEBA), polyalkyl siloxanes, fluorinatedpolymers, perfluoropolyether (PFPE) acrylates, and PFPE methacrylates;and copolymers thereof, and combinations thereof. In certainembodiments, the three-dimensional polymeric printing powder is selectedfrom the group consisting of polyamide 12 (PA12), polyamide 11 (PA11),polyamide 6 (PA6), polyamide 6,12 (PA6,12), low density polyethylene,high density polyethylene, polyhyroxybutyrate (PHB), polyhydroxyvalerate(PHV), polylactic acid (PLA), polyether ether ketone (PEEK), polyetherketone ketone (PEKK); polyoxymethylene (POM), polymethyl methacrylate(PMMA), polystyrene (PS), high-impact polystyrene (HIPS), polyacrylatesand polystyrene-acrylates; polyurethanes (PU),polyacrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol (PVA),polydimethysiloxane (PDMS), polytetrafluoroethylene (PTFE), polyvinylfluoride (PVF), polyvinylidene fluoride (PVDF), and combinationsthereof. In embodiments, the three-dimensional polymeric printing powderis selected from the group consisting of polyamides, polyethylenes,polyalkanoates, polyesters, polyether ether ketones, polycarbonates,polyacrylates, polystyrene-acrylates, polyurethanes, copolymers thereof,and combinations thereof.

In certain embodiments, the three-dimensional polymeric printing powderis selected from the group consisting of low density polyethylene, highdensity polyethylene, polylactic acid, polyoxymethylene, polymethylmethacrylate, polystyrene, acrylonitrile butadiene styrene, polyamide 12(PA12), polyamide 11 (PA11), polyhydroxybutyrate (PHB),polyhydroxyvalerate (PHV), polyether ether ketone (PEEK), copolymersthereof, and combinations thereof.

In embodiments the polymeric powder can be filled by a non-polymericmaterial, including glass beads, mineral fillers, pigments, carbonblack, carbon fiber, fire retardants, ceramic particles, silicaparticles, alumina particles, titania particles and metal particles.

In embodiments wherein the polymeric powder is filled by a metalparticle, any suitable or desired metal particle can be selected. Inembodiments, the metal comprises a metal selected from the groupconsisting of titanium, aluminum, silver, cobalt, chromium, copper,iron, nickel, gold, palladium, stainless steel, alloys thereof, andcombinations thereof. In embodiments, the metal comprises one or moremetal alloys, including titanium alloys such as Ti₆Al₄V, TiAl, aluminumalloys, cobalt-chromium alloys, nickel-based superalloys, and others.For further detail on suitable metal particles, see commonly assigned,co-filed application Ser. No. ______ (Attorney Docket Number20180881US01), which is incorporated by referenced herein in itsentirety.

Suitable specific powders for 3D printing can be obtained from Prodways,who supply PA12-S 1550, PA12-L 1500, PA11-SX 1350, PA11-SX 1450,Ultrasint PA6-X028 polyamide powders, TPU-70 thermoplastic polyurethane,PA12-GFX 2550 glass beads and aluminum filled PA12, PA12-GF 2500, glassbeads filled PA12, PA12-MF 6150 a mineral fabric filled PA12, PA12-CF6500 carbon fiber-filled PA12, PA11-GF 3450, glass filled PA11polyamide, Ultrasint PA6-X028 and PA612-GB 3800 glass bead filledpolyamide 6,12, from CRP Technology S.R.L who supply Windform® SP andWindform® XT 2.0 carbon fiber reinforced composite polyamides, Windform®FX BLACK polyamide powder, Windform® GT polyamide based glass fiberreinforced polyamide with a dark black color; Windform® RL thermoplasticelastomer; Windform® LX 2.0 and Windform® LX 3.0 composite polyamidebased material reinforced with glass fiber, VICTREX® PEEK 150UF10,VICTREX™ PAEK, Victrex™ VICOTE™ 707 polyether ether ketone (PEEK); fromOxford Performance Materials (OPM), who provides OXPEKK® polyetherketone (PEKK); from Evonik who supplies Vestosint® polyamide 12 powdersin d50 sizes of about 6 to about 100 micron; from EOS PrimePart® STpolyether block amide (PEBA) 3D powder, PA 2200 and PA 2201 whitecolored polyamide powder, PA 2202 black pigmented polyamide powder, PA1101 whitish-translucent polyamide 11, PA 1102 black pigmented polyamide12, PA 2210 FR white polyamide 12 powder with a halogen free chemicalflame retardant, PrimePart FR (PA 2241 FR) polyamide 12 with flameretardant, PA 3200 GF glass bead filled polyamide 12, EOS PEEK HP3 whichis a PAEK, EOS PP1101 polypropylene (unfilled), Alumide® polyamide 12aluminum-filled powder, CarbonMide® polyamide 12 carbon fiber-reinforcedpowder, PrimeCast® 101 polystyrene powder, PrimePart PLUS (PA 2221)polyamide 12 powder, and PrimePart® ST (PEBA 2301); from EOS which alsomarkets 3D powders from Advanced Laser Materials (ALM), ALM HP 11-30 acarbon-fiber-reinforced polyamide 11 powder, ALM FR-106 a polyamide 11with flame retardant, and ALM PA 640-GSL polyamide 12 filled with hollowglass microspheres; from ALM 3D PA 802-CF carbon filled polyamide 11,TPE 210 thermoplastic elastomer, PS 200 polystyrene, PA D80-ST unfilledpolyamide 11, PA 650 unfilled polyamide 12, PA 250 unfilled polyamide12, PA 840-GSL glass sphere filled polyamide 11, FR-106 fire-retardantpolyamide 11, PA 606-FR fire-retardant polyamide 12, PA850 and PA 860unfilled polyamide 11, PA 614-GS, PA 615-GS, PA 616-GS and PA 640-GSLglass sphere filled polyamide 12, PA 603-CF carbon fiber filledpolyamide 12, PA 605-A aluminum filled polyamide 12, PA 620-MF mineralfiber filled polyamide 12, PA 415-GS glass sphere filled polyamide 12,HT-23 PEKK carbon fiber filled, TPE 360 copolyester, HP 11-30 carbonfiber filled polyamide 11, and TPE 300 a TPU elastomer powder.

In embodiments, the composition may further include a second largerorganic polymer or copolymer additive comprising an organic cross-linkedsurface additive having a particle size of from about 70 nanometers toabout 250 nanometers in diameter. These larger particles of copolymersurface additive may have an average or median particle size (d50) offrom about 70 nanometers to about 250 nanometers in diameter, or fromabout 80 nanometers to about 200 nanometers in diameter, or from about80 to about 115 nanometers. Advantageously, the teachings of the presentdisclosure render it easier to arrive at the desired particle size, inembodiments, a copolymer size as described herein.

If the second, larger size copolymer organic additive comprising anorganic cross-linked surface additive is present, it can be present inan amount of from about 0.1 parts per hundred by weight to about 5 partsper hundred by weight, or from about 0.2 parts per hundred by weight toabout 0.4 parts per hundred by weight, or 0.3 parts per hundred byweight to about 1.5 parts per hundred by weight, based on 100 parts byweight of polymeric printing powder particles.

The three-dimensional polymeric printing powder composition may includetwo or more emulsion polymerized latex organic polymer or copolymeradditives where the average D50 particle size of the organic polymer orcopolymer additive differs by at least 10 nanometers. In embodiments,the three-dimensional printing composition comprises two or more organicpolymeric additives; wherein a first organic polymeric additive has afirst average D50 particle size; wherein a second organic polymericadditive has a second average D50 particle size; and wherein the firstand second average D50 particle size differ by at least about 10nanometers.

The copolymers utilized as the organic polymeric additive, inembodiments, are not soluble in solvents such as tetrahydrofuran (THF)due to their highly cross-linked nature. Thus, it is not possible tomeasure a number average molecular weight (Mn) or a weight averagemolecular weight (Mw), as measured by gel permeation chromatography(GPC).

The polymer or copolymers utilized as the organic polymeric additive mayhave a glass transition temperature (Tg) of from about 45° C. to about200° C. In embodiments, the organic polymeric additive has a glasstransition temperature of from about 85° C. to about 140° C., inembodiments from about 100° C. to about 130° C.

The organic polymeric surface additive composition may be combined witha 3D printing powder so that the organic polymeric surface additive ispresent in an amount of from about 0.1 percent to about 2 percent byweight, or from about 0.2 percent to about 1.4 percent by weight, orfrom about 0.3 percent to about 1 percent by weight, based upon theweight of the 3D printing powder. In certain embodiments, the organicpolymeric surface additive having a volume average particle diameter offrom about 20 nanometers to less than 70 nanometers is present in anamount of from about 0.1 parts per hundred to about 2 parts per hundredby weight, based on 100 parts by weight of base 3D printing powder. Inembodiments, the polymeric composition may cover from about 5 percent toabout 100 percent, or from about 10 percent to about 100 percent, orfrom about 20 percent to about 50 percent of the surface area of the 3Dpowder particles.

In embodiments, the organic polymeric additive has a total surfaceloading of from about 0.01 to about 5 parts per hundred by weight basedon the weight on the three-dimensional polymeric printing powder.

In embodiments, the three-dimensional polymeric printing powder and theorganic polymeric additive are combined to form a mixture according tothe formula

0.2<(w●D●P)/(0.363●d●p)<1.2

wherein, for the three-dimensional polymeric printing powder, D is theD50 average size of the powder in microns and P is the true bulk densityin grams/cm³; and wherein, for the organic polymeric additive, d is theD50 average particle size in nanometers, p is the true bulk density isgrams/cm³, and w is the weight added to the mixture in parts perhundred.

In embodiments, a 3D printing composition herein may contain the organicpolymeric or copolymeric additive of the present disclosure describedabove, as well as other optional additives, as desired or required.

There can also be blended with the 3D printing powder external additiveparticles including flow aid additives. Examples of these additivesinclude metal oxides such as titanium oxide, silicon oxide, aluminumoxides, cerium oxides, tin oxide, mixtures thereof, and the like;colloidal and amorphous silicas, such as AEROSIL®, metal salts and metalsalts of fatty acids inclusive of zinc stearate, calcium stearate, orlong chain alcohols such as UNILIN 700, and mixtures thereof. Inembodiments, the 3D printing composition herein further comprisescleaning additives selected from the group consisting of stearates,cerium oxide, strontium titanate, and combinations thereof.

In embodiments, silica may be applied to the 3D powder surface forpowder flow, reduced water adsorption, and higher blocking temperature.Titania may be applied for improved powder flow, reduced wateradsorption, or to reduce 3D powder charging, which can make the 3Dparticles stick to each other. Zinc stearate, calcium stearate and/ormagnesium stearate may optionally also be used as an external additivefor providing lubricating properties of the surface, which can helppowder flow as well as reduced water adsorption. In embodiments, acommercially available zinc stearate known as Zinc Stearate L, obtainedfrom Ferro Corporation, may be used. The external surface additives maybe used with or without a coating.

In embodiments, the 3D printing composition further comprises a memberof the group consisting of a silica surface additive, a titania surfaceadditive, and combinations thereof. In embodiments, the 3D printingcomposition comprises a silica additive, a titania additive, or acombination thereof, and at least one of the silica or titania additiveshas a hydrophobic treatment, in embodiments, one or more of the silicaor titania additives has a polydimethylsiloxane hydrophobic treatment.

Each of these external additives may be present in an amount from about0 parts per hundred to about 3 parts per hundred of the 3D printingpowder, in embodiments from about 0.25 parts per hundred to about 2.5parts per hundred of the 3D printing powder, although the amount ofadditives can be outside of these ranges. In embodiments, thecompositions herein may include, for example, from about 0 parts perhundred to about 3 parts per hundred titania, from about 0 parts perhundred to about 3 parts per hundred silica, and from about 0 parts perhundred to about 3 parts per hundred zinc stearate.

In embodiments, in addition to the organic polymeric additive of thepresent disclosure, the 3D printing composition may also possess silicain amounts of from about 0.1 parts per hundred to about 5 parts perhundred by weight of the 3D printing powder, in embodiments from about0.2 parts per hundred to about 2 parts per hundred by weight of the 3Dprinting powder, and titania in amounts of from about 0 parts perhundred to about 3 parts per hundred by weight of the 3D printingpowder, in embodiments from about 0.1 parts per hundred to about 1 partsper hundred by weight of the 3D printing powder.

The 3D printing compositions herein can be used for any suitable ordesired process. The 3D printing compositions can be used in laser beammelting printing processes or selective laser sintering processes. Inembodiments, a method herein comprises providing a three-dimensionalpolymeric printing powder having an organic polymeric additive on atleast a portion of an external surface of the three-dimensionalpolymeric printing powder; and optionally, further having an inorganicadditive on at least a portion of an external surface of thethree-dimensional polymeric printing powder; and exposing thethree-dimensional polymeric printing powder having the organic polymericadditive and optional inorganic additive to a laser to fuse the three-dimensional polymeric printing powder.

Also provided is a method of selective laser sintering comprisingproviding a 3D printing composition as described herein; and exposingthe 3D printing composition to a laser to fuse the printing powder.

Any three dimensional printer or type of SLS printer can be employed.See, for example, U.S. Patent Publication 2018/0022043, which is herebyincorporated by reference herein in its entirety.

EXAMPLES

The following Examples are being submitted to further define variousspecies of the present disclosure. These Examples are intended to beillustrative only and are not intended to limit the scope of the presentdisclosure. Also, parts and percentages are by weight unless otherwiseindicated.

Organic polymeric latex additives were produced by emulsionpolymerization. The 5-gallon runs were post-processed for 1 hour at 77°C. following by a 2 hour ramp to 87° C. followed by a 1 hour process at° C. The 2-L runs were post-processed for 1 hour at 77° C.

It has been discovered that particle sizes of greater than 70 nanometersmay degrade flow, but provide excellent blocking resistance. Particlesizes of about less than 70 nanometers will provide improved flow, aswell as provide some blocking resistance. In embodiments, a small sizelatex, in embodiments of about 47 nanometers in diameter, was preparedto demonstrate flow improvement for the 3D particles.

Process for preparation of 5-gallon polymeric latex. A polymeric latexwas synthesized by a semi-continuous starve-fed emulsion polymerizationprocess. An emulsified monomer mixture was prepared in a portable tankby mixing monomers, 2.671 kilograms cyclohexyl methacrylate (CHMA), 0.9kilograms divinylbenzene 55% technical grade (DVB-55), and 28.81 grams2- (dimethylamino)ethyl methacrylate (DMAEMA), into a surfactantsolution containing 922.14 grams 20.9% Tayca BN2060 solution and 3.591kilograms deionized water.

A separate aqueous phase mixture was prepared in a 5-gallon reactionvessel by mixing 395.2 grams 20.9% Tayca BN2060 (a dodecylbenzenesulfonate anionic emulsifier) solution with 9.265 kilograms deionizedwater which was then heated to 77° C. with continuous mixing at 225 rpm.A polymer seed was prepared by adding 3% of the emulsified monomer intothe reactor and mixing for a minimum of 15 minutes. After the reactor'stemperature reached around 77° C., the initiator solution of 0.403kilograms deionized water and 13.83 grams ammonium persulfate (APS) wereadded over 7 minutes to polymerize the seed particles. Following a 15minute wait time, the remaining emulsified monomer was added at acontrolled feed rate to the reactor over a two hours period topolymerize and grow the polymer seed particles. Once the monomer feedingis complete, the reactor was held at the reaction temperature for anextra hour, then ramped over 2 hours to an elevated temperature of 87°C. and held for an additional 2 hours to lower the residual monomerslevels. During the post reaction process the latex was buffered with 0.1M sodium hydroxide (NaOH) solution to maintain pH between 5.5 and 6.0.The latex was then cooled to room temperature and discharged through 5micron welded polypropylene filter bag. The resulting product was anaqueous polymer latex that contains about 20 weight percent solids. Thefinal particle size of the latex was 47 nanometers. Particle size wasdetermined using a Nanotrac NPA252 with the following settings:Distribution—Volume, Progression—Geom 4 Root, Residuals—Enabled,Particle Refractive Index—1.59, Transparency—Transparent, and ParticleShape—Spherical.

The 5-gallon latex was spray dried using a dual liquid nozzle DL41 spraydryer from Yamato Scientific Co. with drying conditions of:

Atomizing pressure: 4 kgf/cm²

Sample feed rate: 3 (0.6 liters/minute)

Temperature: 140° C.

Aspirator flow rate: 4 m³/minute

Table 1 shows formulations for the organic polymeric additive examples.Table 2 shows process parameters. Table 3 shows particle size andresidual monomers. DMAEMA residual monomer is not shown as typicallythis is very low and is not typically detectable.

Table 1

TABLE 1 % SLS Example % Solids % SLS Upfront % APS % Seed 1 20 0.4 44.150.38 5 2 20 0.4 44.15 0.38 5 3 20 0.4 50 0.38 5 4 20 0.5 50 0.38 5 5 200.5 50 0.5 5 6 20 0.5 50 0.5 3 7 20 0.5 50 0.65 2.5 8 18 0.48 50 0.38 59 20 Tayca 30 0.38 5 1.24 10 20 Tayca 30 0.38 3 1.24 SLS = sodium laurylsulphate. APS = ammonium persulfate.

TABLE 2 Monomer Feed Example Reactor Size Mixing rpm Time (Hours) 1 2Liter 400/450 2 2 5 Gallon 225/275 2 3 2 Liter 400/450 2 4 2 Liter400/450 2 5 2 Liter 400/450 2 6 5 Gallon 250/300 2 7 2 Liter 450/500 2 82 Liter 400/450 2 9 2 Liter 400/450 2 10 5 Gallon 225/275 2

TABLE 3 GC Residual Monomers Particle Size CHMA DVB Total Example(Nanometers) (ppm) (ppm) (ppm) 1 60.1 NA NA NA 2 63.2 25 16 41 3 68.2 NANA NA 4 57.4 NA NA NA 5 56.8 NA NA NA 6 58.6 27 10 37 7 74.5 NA NA NA 854.0 NA NA NA 9 49 NA NA NA 10 47 <30  <40  <70  NA = not applicable. ND= not detected. Polymer Particles.

The 3D polymeric powder can be any suitable or desired powder asdescribed hereinabove including polyamides, polyethylenes,polyalkanoates, polyesters, polyether ether ketones, polycarbonates,polyacrylates, polystyrene-acrylates, polyurethanes, copolymers thereof,and combinations thereof. In embodiments, the 3D polymeric powder may becomprised of polyamide such as PA12, PA11, high density polyethylene,polylactic acid (PLA), polyalkanoates (PHB, PHV) and other polyesters,PEEK and others.

The 3D particles chosen for the present embodiments were PA12 powder ofaverage size of about 54 microns and particle true density of 1.14 g/cm³prepared at the Xerox Research Center of Canada.

Example 11

Into a 50 gallon reactor is added 12.63 kilograms of polyamide PA12granular resin and optionally 126.3 grams of silica powder that isdissolved in 129.85 kilograms of N-methyl-2-pyrrolidone (NMP) solventwith mixing at elevated temperature in an inert atmosphere. Once all thepolymer is dissolved at 180° C. the solution is quickly cooled to 130°C. to precipitate the polymer out of solution. The material is furthercooled to room temperature with agitation and then discharged and rinsedwith more NMP and then deionized water and methanol. The material isvacuum dried at elevated temperature such as 90° C. and then storeduntil required for additive blending. The average size of theseparticles was 54 microns.

FIGS. 1, 2, 3, and 4 show scanning electron micrograph (SEM) images ofthe irregularly shaped PA12 particles of Example 11. FIG. 1 shows ascanning electron micrograph (SEM) image of PA12 polyamide particles at50× magnification. FIG. 2 shows a scanning electron micrograph (SEM)image of PA12 polyamide particles at 100× magnification. FIG. 3 shows ascanning electron micrograph (SEM) image of PA12 polyamide particles at400× magnification. FIG. 4 shows a scanning electron micrograph (SEM)image of PA12 polyamide particles at 600× magnification.

Organic Polymeric Additive Blending.

Mathematically the general ideal formula for the coverage of sphericalorganic surface additive on a larger particle surface is given by:

0.2<(w●D●P)/(0.363●d●p)<1.2

where for the 3D powder, D is the D50 average size in microns and P isthe true density in grams/cm³, and for the organic emulsion polymerizedlatex, d is the D50 average size in nanometers, p is the true density ingrams/cm³, and w is the weight added to the mixture in pph.

In general, effective amounts of an additive for flow or blocking rangecan be from about 0.2 to 1.2 of full coverage. The value of 0.2,indicates 0.2 of the surface is covered, and a value of 1 indicates fullcoverage of the surface. If the particles have some surface roughness orare not truly spherical they will require somewhat higher coverage astheir surface area is higher than expected based on the size anddensity, so a value as high as 1.2 may be required, as indicated in theformula.

For the PA12 powder having a particle size of 54 microns, a density of1.15 g/cm³, and the organic additive of Example 10 having a particlesize of 47 nanometers and a density of 1.14 g/cm³, w=0.32 pph for aboutfull coverage.

It is also desirable that the particle shape is spherical to induce afree flowing powder. To access particle flow, aerated and tap bulkdensity are measured and then that data is used to calculate the Hausnerratio HR. A material with a Hausner ratio HR<1.25 is an indication of afree flowing powder behavior, 1.25 to 1.5 as moderate flowing, and aHR>1.5 means a poor flowing powder with fluidization problems due tohigh cohesive forces. Particle density impacts the fluid bed densitywhich is influenced by the particle shape. An alternate measurement forflow of a powder is angle of repose, the lower the angle of repose thebetter the flow of the powder. The following Table 4 categorizes flowaccording to R. L. Carr, Evaluating Flow Properties of Solids, Chem.Eng. 1965, 72, 163-168.

TABLE 4 Flow Property Angle of Repose (degrees) Excellent 25-30 Good31-35 Fair - aid not needed 36-40 Passable - may hang up 41-45 Poor -must agitate, vibrate 46-55 Very poor 56-65 Very, very poor >66

Comparative Example 12

Using 50 grams of PA12 particles of Example 11, the particle bulkdensity and angle of repose were evaluated. Both aerated bulk densityand tapped bulk density were measured and used to determine compactionwhich is reported as the Hausner Ratio without surface additives. SeeTable 4.

Example 13

PA12 With Organic Additive As A Flow Agent. Dry particles of the organicadditive of Example 10 at 0.32 pph (1.5 grams) was added to 50 grams ofPA12 powder of Example 12 and mixed on a lab SKM Mill at 13,500 rpm for30 seconds. After the blending step was completed, the blended materialwas sieved through a 150 micron stainless steel sieve and the materialwas put into a bottle and evaluated for flow and angle of repose.Evaluation of flow properties of Comparative Example 12 compared toExample 13 is provided in Table 5.

FIG. 5 shows a scanning electron micrograph (SEM) image of the PA12polyamide particles with the organic additive added in a dry blendingprocess of Example 14 at 15,000× magnification.

TABLE 5 Bulk Density Angle of Aerated Tapped Bulk Compaction Repose BulkDensity Density (Hausner Angle (°) Example (g/cc) (g/cc) Ratio) AverageComparative 0.33 0.44 1.35 40.0 Example 12 Example 13 0.37 0.46 1.2233.6

The examples show that the organic polymeric additive has effectivelychanged the 3D powder from a moderately flowing powder to a free flowingpowder, from the Hausner ratio, as well as a significant improvement inlowering the angle of repose. According to the Table 4, the originalPA12 particles are borderline for flow at 40 degrees, at the edge of“fair—aid not needing” (aid here means flow aid), nearing 41 degrees,which is “passable—may hang up”. With the present organic polymericadditive added, the flow is rated “good” based on angle of repose.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims. Unless specifically recited in aclaim, steps or components of claims should not be implied or importedfrom the specification or any other claims as to any particular order,number, position, size, shape, angle, color, or material.

1. A composition comprising: a three-dimensional polymeric printingpowder; wherein the three-dimensional polymeric printing powder isselected from the group consisting of polyamide 12 (PA12), polyamide 11(PA11), polyamide 6 (PA6), polyamide 6,12 (PA6,12), low densitypolyethylene, high density polyethylene, polyhyroxybutyrate (PHB),polyhydroxyvalerate (PHV), polylactic acid (PLA), polyether ether ketone(PEEK), polyether ketone ketone (PEKK); polyoxymethylene (POM);polymethyl methacrylate (PMMA), polystyrene (PS), high-impactpolystyrene (HIPS), polyacrylates, polystyrene-acrylates; polyurethanes(PU), polyacrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol(PVA), polydimethysiloxane (PDMS), polytetrafluoroethylene (PTFE),polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), andcombinations thereof; an organic polymeric additive on at least aportion of an external surface of the three-dimensional polymericprinting powder; wherein the organic polymeric additive is optionallycross-linked; wherein the organic polymeric additive is a polymer orcopolymer comprising a first monomer having a high carbon to oxygenratio of from about 3 to about 8; optionally, a second monomercomprising two or more vinyl groups, wherein the second monomer, ifpresent, is present in the copolymer in an amount of from greater thanabout 8 percent by weight to about 40 percent by weight, based on theweight of the copolymer; and optionally, a third monomer comprising anamine, wherein the third monomer, if present, is present in an amount offrom about 0.1 percent by weight to about 1.5 percent by weight, basedon the weight of the copolymer; and a surfactant having a minimumsurface tension of less than about 45 mN/m: wherein the organicpolymeric additive comprises latex particles having a volume averageparticle diameter of from about 20 nanometers to less than 50nanometers; and optionally, an inorganic additive on at least a portionof an external surface of the three-dimensional polymeric printingpowder.
 2. (canceled)
 3. The composition of claim 1, wherein the organicadditive comprises at least one non-cross-linkable polymerizablemonomer; or wherein the organic additive comprises at least onecross-linkable polymerizable monomer; or wherein the organic additivecomprises a combination of at least one non- cross-linkablepolymerizable monomer and at least one cross-linkable polymerizablemonomer.
 4. The composition of claim 1, wherein the organic polymericadditive comprises a cross-linkable monomer containing 2 or more vinylgroups; and wherein the cross-linkable monomer containing 2 or morevinyl groups is present in the organic polymeric additive in an amountof greater than zero up to about 40 percent, by weight, based on thetotal weight of the organic polymeric additive.
 5. The composition ofclaim 1, wherein the organic polymeric additive comprises an acidicmonomer, a basic monomer, or a combination thereof.
 6. The compositionof claim 1, wherein the organic polymeric additive comprises a basicmonomer having a nitrogen-containing group; and wherein the basicmonomer having a nitrogen-containing group is present in the organicpolymeric additive in an amount of less than about 1.5 percent, byweight, based on the total weight of the organic polymeric additive. 7.The composition of claim 1, wherein the organic polymeric additivecomprises an acidic monomer having an acidic group selected from thegroup consisting of acrylic acid, beta-carboxyethyl acrylate, andcombinations thereof; and wherein the acidic monomer is present in theorganic polymeric additive in an amount of less than about 4 percent, byweight, based on the total weight of the organic polymeric additive. 8.The composition of claim 1, wherein the organic polymeric additivecomprises a monomer selected from the group consisting of an acrylatemonomer, a methacrylate monomer, and combinations thereof.
 9. Thecomposition of claim 1, wherein the organic polymeric additive compriseslatex particles having a volume average particle diameter of from about30 nanometers to about 140 nanometers.
 10. The composition of claim 1,wherein the composition comprises two or more organic polymericadditives; wherein a first organic polymeric additive has a firstaverage D50 particle size; wherein a second organic polymeric additivehas a second average D50 particle size; and wherein the first and secondaverage D50 particle size differ by at least about 10 nanometers. 11.The composition of claim 1, wherein the organic polymeric additive has atotal surface loading of from about 0.01 to about 5 parts per hundred byweight based on the weight of the three-dimensional polymeric printingpowder.
 12. The composition of claim 1, wherein the three-dimensionalpolymeric printing powder and the organic polymeric additive arecombined to form a mixture according to the formula0.2<(w●D●P)/(0.363●d●p)<1.2 wherein, for the three-dimensional polymericprinting powder, D is the D50 average size of the powder in microns andP is the true bulk density in grams/cm³; and wherein, for the organicpolymeric additive, d is the D50 average particle size in nanometers, pis the true bulk density is grams/cm³, and w is the weight added to themixture in parts per hundred.
 13. The composition of claim 1, whereinthe organic polymeric additive comprises latex particles produced byemulsion polymerization of at least one monomer and a the surfactant;wherein the surfactant comprises a member of the group consisting of ananionic surfactant, a cationic surfactant, a non-ionic surfactant, andcombinations thereof; and wherein the surfactant has a minimum surfacetension of less than about 45 mN/m.
 14. The composition of claim 1,wherein the organic polymeric additive comprises latex particlesproduced by emulsion polymerization of at least one monomer and thesurfactant; wherein the surfactant comprises a member of the groupconsisting of sodium dodecylbenzene sulfonate, sodium dodecyl sulphate,and combinations thereof.
 15. The composition of claim 1, wherein theorganic polymeric additive has a glass transition temperature of fromabout 45° C. to about 200° C.
 16. (canceled)
 17. (canceled)
 18. Aprocess comprising: providing a three-dimensional polymeric printingpowder; wherein the three-dimensional polymeric printing powder isselected from the group consisting of polyamide 12 (PA12), polyamide 11(PA11), polyamide 6 (PA6), polyamide 6,12 (PA6,12), low densitypolyethylene, high density polyethylene, polyhyroxybutyrate (PHB),polyhydroxyvalerate (PHV), polylactic acid (PLA), polyether ether ketone(PEEK), polyether ketone ketone (PEKK); polyoxymethylene (POM);polymethyl methacrylate (PMMA), polystyrene (PS), high-impactpolystyrene (HIPS), polyacrylates, polystyrene-acrylates; polyurethanes(PU), polyacrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol(PVA), polydimethysiloxane (PDMS), polytetrafluoroethylene (PTFE),polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), andcombinations thereof; providing an organic polymeric additive on atleast a portion of an external surface of the three-dimensionalpolymeric printing powder; wherein the organic polymeric additive is apolymer or copolymer comprising a first monomer having a high carbon tooxygen ratio of from about 3 to about 8; optionally, a second monomercomprising two or more vinyl groups, wherein the second monomer, ifpresent, is present in the copolymer in an amount of from greater thanabout 8 percent by weight to about 40 percent by weight, based on theweight of the copolymer; and optionally, a third monomer comprising anamine, wherein the third monomer, if present, is present in an amount offrom about 0.1 percent by weight to about 1.5 percent by weight, basedon the weight of the copolymer; and a surfactant having a minimumsurface tension of less than about 45 mN/m; wherein the organicpolymeric additive comprises latex particles having a volume averageparticle diameter of from about 20 nanometers to less than 50nanometers; and optionally, further providing an inorganic additive onat least a portion of an external surface of the three-dimensionalpolymeric printing powder; wherein the organic polymeric additive isprepared by emulsion polymerization.
 19. A method comprising: providinga three-dimensional polymeric printing powder having an organicpolymeric additive on at least a portion of an external surface of thethree-dimensional polymeric printing powder; wherein the organicpolymeric additive is a polymer or copolymer comprising a first monomerhaving a high carbon to oxygen ratio of from about 3 to about 8;optionally, a second monomer comprising two or more vinyl groups,wherein the second monomer, if present, is present in the copolymer inan amount of from greater than about 8 percent by weight to about 40percent by weight, based on the weight of the copolymer; and optionally,a third monomer comprising an amine, wherein the third monomer, ifpresent, is present in an amount of from about 0.1 percent by weight toabout 1.5 percent by weight, based on the weight of the copolymer; asurfactant having a minimum surface tension of less than about 45 mN/m;wherein the organic polymeric additive comprises latex particles havinga volume average particle diameter of from about 20 nanometers to lessthan 50 nanometers; and optionally, further having an inorganic additiveon at least a portion of an external surface of the three-dimensionalpolymeric printing powder; wherein the three-dimensional polymericprinting powder is selected from the group consisting of polyamide 12(PA12), polyamide 11 (PA11), polyamide 6 (PA6), polyamide 6,12 (PA6,12),low density polyethylene, high density polyethylene, polyhyroxybutyrate(PHB), polyhydroxyvalerate (PHV), polylactic acid (PLA), polyether etherketone (PEEK), polyether ketone ketone (PEKK); polyoxymethylene (POM);polymethyl methacrylate (PMMA), polystyrene (PS), high-impactpolystyrene (HIPS), polyacrylates, polystyrene-acrylates; polyurethanes(PU), polyacrylonitrile-butadiene-styrene (ABS), polyvinyl alcohol(PVA), polydimethysiloxane (PDMS), polytetrafluoroethylene (PTFE),polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), andcombinations thereof; and exposing the three-dimensional polymericprinting powder having the organic polymeric additive and optionalinorganic additive to a laser to fuse the three-dimensional polymericprinting powder.
 20. The method of claim 19, wherein the methodcomprises a laser beam melting printing process or a selective lasersintering process.
 21. (canceled)
 22. The process of claim 18, whereinthe organic additive is a polymer or copolymer comprising a firstmonomer having a high carbon to oxygen ratio of from about 3 to about 8;optionally, a second monomer comprising two or more vinyl groups,wherein the second monomer, if present, is present in the copolymer inan amount of from greater than about 8 percent by weight to about 40percent by weight, based on the weight of the copolymer; and optionally,a third monomer comprising an amine, wherein the third monomer, ifpresent, is present in an amount of from about 0.1 percent by weight toabout 1.5 percent by weight, based on the weight of the copolymer; andwherein the organic polymeric additive comprises latex particles havinga volume average particle diameter of from about 20 nanometers to lessthan 50 nanometers.
 23. The process of claim 19, wherein the organicadditive is a polymer or copolymer comprising a first monomer having ahigh carbon to oxygen ratio of from about 3 to about 8; optionally, asecond monomer comprising two or more vinyl groups, wherein the secondmonomer, if present, is present in the copolymer in an amount of fromgreater than about 8 percent by weight to about 40 percent by weight,based on the weight of the copolymer; and optionally, a third monomercomprising an amine, wherein the third monomer, if present, is presentin an amount of from about 0.1 percent by weight to about 1.5 percent byweight, based on the weight of the copolymer; and wherein the organicpolymeric additive comprises latex particles having a volume averageparticle diameter of from about 20 nanometers to less than 50nanometers.